Shaped abrasive particles and methods of forming same

ABSTRACT

A method of forming a shaped abrasive particle includes applying a mixture into a shaping assembly within an application zone and directing an ejection material at the mixture in the shaping assembly under a predetermined force, removing the mixture from the shaping assembly and forming a precursor shaped abrasive particle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/592,430, entitled “SHAPED ABRASIVE PARTICLES AND METHODS OF FORMINGSAME,” by Bauer et al., filed May 11, 2017, which is a continuation ofU.S. patent application Ser. No. 15/213,758, entitled “SHAPED ABRASIVEPARTICLES AND METHODS OF FORMING SAME,” by Bauer et al., filed Jul. 19,2016, now U.S. Pat. No. 9,688,893 issued Jun. 27, 2017 which is acontinuation of U.S. patent application Ser. No. 14/925,191, entitled“SHAPED ABRASIVE PARTICLES AND METHODS OF FORMING SAME,” by Bauer etal., filed Oct. 28, 2015, now U.S. Pat. No. 9,428,681, issued Aug. 30,2016, which is a continuation of U.S. patent application Ser. No.13/901,362, entitled “SHAPED ABRASIVE PARTICLES AND METHODS OF FORMINGSAME,” by Bauer et al., filed May 23, 2013, now U.S. Pat. No. 9,200,187,issued Dec. 1, 2015, which claims priority under 35 U.S.C. § 119(e) toU.S. Patent Application No. 61/650,673 entitled “SHAPED ABRASIVEPARTICLES AND METHODS OF FORMING SAME,” by Bauer et al., filed May 23,2012, which are assigned to the current assignee hereof and incorporatedherein by reference in their entireties.

BACKGROUND Field of the Disclosure

The following is directed to shaped abrasive particles, and moreparticularly, to a process of forming shaped abrasive particles and theresulting particles.

Description of the Related Art

Abrasive articles incorporating abrasive particles are useful forvarious material removal operations including grinding, finishing,polishing, and the like. Depending upon the type of abrasive material,such abrasive particles can be useful in shaping or grinding variousmaterials in the manufacturing of goods. Certain types of abrasiveparticles have been formulated to date that have particular geometries,such as triangular shaped abrasive particles and abrasive articlesincorporating such objects. See, for example, U.S. Pat. Nos. 5,201,916;5,366,523; and 5,984,988.

Previously, three basic technologies that have been employed to produceabrasive particles having a specified shape, which are fusion,sintering, and chemical ceramic. In the fusion process, abrasiveparticles can be shaped by a chill roll, the face of which may or maynot be engraved, a mold into which molten material is poured, or a heatsink material immersed in an aluminum oxide melt. See, for example, U.S.Pat. No. 3,377,660. In sintering processes, abrasive particles can beformed from refractory powders having a particle size of up to 10micrometers in diameter. Binders can be added to the powders along witha lubricant and a suitable solvent to form a mixture that can be shapedinto platelets or rods of various lengths and diameters. See, forexample, U.S. Pat. No. 3,079,242. Chemical ceramic technology involvesconverting a colloidal dispersion or hydrosol (sometimes called a sol)to a gel or any other physical state that restrains the mobility of thecomponents, drying, and firing to obtain a ceramic material. See, forexample, U.S. Pat. Nos. 4,744,802 and 4,848,041.

Rudimentary molding processes have been disclosed as potentially usefulin forming limited shaped abrasive particles, such as those disclosed inU.S. Pat. Nos. 5,201,916, 5,366,523, 5,584,896, and U.S. Pat. Publs.2010/0151195, 2010/0151195. Other processes of forming shaped abrasiveparticles have been disclosed; see for example, U.S. Pat. Nos.6,054,093, 6,228,134, 5,009,676, 5,090,968, and 5,409,645.

The industry continues to demand improved abrasive materials andabrasive articles.

SUMMARY

According to one aspect, a method includes applying a mixture into ashaping assembly within an application zone, and directing an ejectionmaterial at the mixture in the shaping assembly under a predeterminedforce, removing the mixture from the shaping assembly and forming aprecursor shaped abrasive particle.

According to a second aspect, a method includes forming a precursorshaped abrasive particle in less than about 18 minutes, wherein formingincludes applying a mixture into a shaping assembly within anapplication zone and removing the mixture from the shaping assembly toform a precursor shaped abrasive particle.

In yet another aspect, a method includes extruding a mixture having aviscosity of at least about 4×10³ Pa s into an opening in a shapingassembly within an application zone and removing the mixture from theopening by applying an external force to the mixture to form a precursorshaped abrasive particle.

For another aspect, a system for forming shaped abrasive particlesincludes an application zone comprising a shaping assembly, a firstportion having an opening and configured to be filled with a mixture, asecond portion abutting the first portion, and an ejection zonecomprising an ejection assembly configured to direct an ejectionmaterial toward the opening in the first portion of the shapingassembly.

According to another aspect, a system for forming precursor shapedabrasive particles can have a batch productivity of at least about 0.1kg/min/m2 shaping surface.

In another aspect, a batch of shaped abrasive particles can include afirst portion comprising a shaped abrasive particle having tortuouscontour.

For another aspect, a shaped abrasive particle includes a body having atortuous contour.

Still, in another aspect, a shaped abrasive particle has a bodyincluding an arrowhead shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerousfeatures and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1 includes a schematic of a system for forming a shaped abrasiveparticle in accordance with an embodiment.

FIG. 2 includes an illustration of a portion of the system of FIG. 1 inaccordance with an embodiment.

FIGS. 3A-3C include perspective view illustrations of shaped abrasiveparticles in accordance with an embodiment.

FIG. 4 includes a coated abrasive including shaped abrasive particlesaccording to an embodiment.

FIG. 5 includes a bonded abrasive including shaped abrasive particlesaccording to an embodiment.

FIG. 6 includes a side view image of a shaped abrasive particleaccording to an embodiment.

FIG. 7 includes a side view image of a shaped abrasive particleaccording to an embodiment.

FIG. 8 includes an illustration of a side view of a shaped abrasiveparticle having flashing in accordance with an embodiment.

FIG. 9 includes a perspective view image of a shaped abrasive particleaccording to an embodiment.

FIG. 10 includes a top view image of a shaped abrasive particleaccording to an embodiment.

FIG. 11A includes side view images of shaped abrasive particles formedaccording to an embodiment.

FIG. 11B includes a top view image of a plurality of shaped abrasiveparticles formed according to an embodiment.

FIG. 12 includes a plot of specific grinding energy versus cumulativematerial removed for a conventional sample and a sample representativeof an embodiment.

FIG. 13 includes a top view image of a plurality of shaped abrasiveparticles formed according to an embodiment.

DETAILED DESCRIPTION

The systems and methods herein may be utilized in forming shapedabrasive particles. The shaped abrasive particles may be utilized invarious applications, including for example coated abrasives, bondedabrasives, free abrasives, and a combination thereof. Various other usesmay be derived for the shaped abrasive particles.

FIG. 1 includes an illustration of a system for forming a shapedabrasive particle in accordance with an embodiment. As illustrated, thesystem 100 can further include a die 103 configured to facilitatedelivery of a mixture 101 contained within a reservoir 102 of the die103 to a shaping assembly 151. The process of forming a shaped abrasiveparticle can be initiated by forming a mixture 101 including a ceramicmaterial and a liquid. In particular, the mixture 101 can be a gelformed of a ceramic powder material and a liquid, wherein the gel can becharacterized as a shape-stable material having the ability to hold agiven shape even in the green state (i.e., unfired or undried gel). Inaccordance with an embodiment, the gel can be formed of the ceramicpowder material as an integrated network of discrete particles.

The mixture 101 can be formed to have a particular content of solidmaterial, such as the ceramic powder material. For example, in oneembodiment, the mixture 101 can have a high solids content, includingfor example, a solids content of at least about 25 wt %, such as atleast about 35 wt %, at least about 42 wt %, at least about 44 wt %, atleast about 46 wt %, at least about 48 wt %, at least about 50 wt %, oreven at least about 51 wt % for the total weight of the mixture 101.Still, in at least one non-limiting embodiment, the solid content of themixture 101 can be not greater than about 80 wt %, not greater thanabout 75 wt %, such as not greater than about 70 wt %, not greater thanabout 65 wt %, not greater than about 60 wt %, not greater than about 58wt %, not greater than about 56 wt %, or even not greater than about 54wt %. It will be appreciated that the content of the solids materials inthe mixture 101 can be within a range between any of the minimum andmaximum percentages noted above.

According to one embodiment, the ceramic powder material can include anoxide, a nitride, a carbide, a boride, an oxycarbide, an oxynitride, anda combination thereof. It will be appreciated, that in certainalternative embodiments, in place of a ceramic powder material, one maychoose to use a precursor of a ceramic powder material. A precursor canbe a material, which may or may not be in a powder form that isconfigured to change at least a portion of its composition or physicalproperties during processing to form a ceramic material. In particularinstances, the ceramic material can include alumina. More specifically,the ceramic material may include a boehmite material, which may be aprecursor of alpha alumina. The term “boehmite” is generally used todenote alumina hydrates including mineral boehmite, typically beingAl2O3.H2O and having a water content on the order of 15%, as well aspseudoboehmite, having a water content higher than 15%, such as 20-38%by weight. It is noted that boehmite (including pseudoboehmite) has aparticular and identifiable crystal structure, and accordingly uniqueX-ray diffraction pattern, and as such, is distinguished from otheraluminous materials including other hydrated aluminas such as ATH(aluminum trihydroxide) a common precursor material used herein for thefabrication of boehmite particulate materials.

Furthermore, the mixture 101 can be formed to have a particular contentof liquid material. Some suitable liquids may include inorganicmaterials, such as water or various organic media such as alcohols andthe like. In accordance with one embodiment, the mixture 101 can beformed to have a liquid content less than the solids content of themixture 101. In more particular instances, the mixture 101 can have aliquid content of at least about 20 wt %, such as at least about 25 wt %for the total weight of the mixture 101. In other instances, the amountof liquid within the mixture 101 can be greater, such as at least about35 wt %, at least about 40 wt %, at least about 42 wt %, or even atleast about 44 wt %. Still, in at least one non-limiting embodiment, theliquid content of the mixture can be not greater than about 80 wt %,such as not greater than about 65 wt %, not greater than about 60 wt %,not greater than about 55 wt %, not greater than about 52 wt %, notgreater than about 49 wt %. It will be appreciated that the content ofthe liquid in the mixture 101 can be within a range between any of theminimum and maximum percentages noted above.

Furthermore, to facilitate processing and forming shaped abrasiveparticles according to embodiments herein, the mixture 101 can have aparticular storage modulus. For example, the mixture 101 can have astorage modulus of at least about 1×10⁴ Pa, such as at least about 4×10⁴Pa, such as at least about 4.4×10⁴ Pa, at least about 5×10⁴ Pa, at leastabout 6×10⁴ Pa, at least about 8×10⁴ Pa, at least about 10×10⁴ Pa, atleast about 15×10⁴ Pa, at least about 20×10⁴ Pa, at least about 30×10⁴Pa, or even at least about 40×10⁴ Pa. In at least one non-limitingembodiment, the mixture 101 may have a storage modulus of not greaterthan about 80×10⁴ Pa, not greater than about 70×10⁴ Pa, not greater thanabout 65×10⁴ Pa, or even not greater than about 60×10⁴ Pa. It will beappreciated that the storage modulus of the mixture 101 can be within arange between any of the minimum and maximum values noted above. Thestorage modulus can be measured via a parallel plate system using ARESor AR-G2 rotational rheometers, with Peltier plate temperature controlsystems. For testing, the mixture 101 can be extruded within a gapbetween two plates that are set to be approximately 8 mm apart from eachother. After extruding the gel into the gap, the distance between thetwo plates defining the gap is reduced to 2 mm until the mixture 101completely fills the gap between the plates. After wiping away excessmixture, the gap is decreased by 0.1 mm and the test is initiated. Thetest is an oscillation strain sweep test conducted with instrumentsettings of a strain range between 0.01% to 100%, at 6.28 rad/s (1 Hz),using 25-mm parallel plate and recording 10 points per decade. Within 1hour after the test completes, lower the gap again by 0.1 mm and repeatthe test. The test can be repeated at least 6 times. The first test maydiffer from the second and third tests. Only the results from the secondand third tests for each specimen should be reported.

Furthermore, to facilitate processing and forming shaped abrasiveparticles according to embodiments herein, the mixture 101 can have aparticular viscosity. For example, the mixture 101 can have a viscosityof at least about 4×10³ Pa s, at least about 5×10³ Pa s, at least about6×10³ Pa s, at least about 8×10³ Pa s, at least about 10×10³ Pa s, atleast about 20×10³ Pa s, at least about 30×10³ Pa s, at least about40×10³ Pa s, at least about 50×10³ Pa s, at least about 60×10³ Pa s, atleast about 65×10³ Pa s. In at least one non-limiting embodiment, themixture 101 may have a viscosity of not greater than about 100×10³ Pa s,not greater than about 95×10³ Pa s, not greater than about 90×10³ Pa s,or even not greater than about 85×10³ Pa s. It will be appreciated thatthe viscosity of the mixture 101 can be within a range between any ofthe minimum and maximum values noted above. The viscosity can bemeasured in the same manner as the storage modulus as described above.

In at least one embodiment, to facilitate processing and forming shapedabrasive particles according to embodiments herein, the mixture 101 canhave a particular yield stress. For example, the mixture 101 can have ayield stress of at least about 1.5×10³ Pa, at least about 4×10³ Pa atleast about 5×10³ Pa, at least about 6×10³ Pa, at least about 8×10³ Pa,at least about 10×10³ Pa, at least about 12×10³ Pa s, at least about20×10³ Pa s, at least about 30×10³ Pa, at least about 40×10³ Pa, or evenat least about 65×10³ Pa. In at least one non-limiting embodiment, themixture 101 may have a yield stress of not greater than about 100×10³Pa, not greater than about 80×10³ Pa, not greater than about 60×10³ Pa,or even not greater than about 50×10³ Pa. It will be appreciated thatthe yield stress of the mixture 101 can be within a range between any ofthe minimum and maximum values noted above. The yield stress can bemeasured in the same manner as the storage modulus as described above.

The rheological characteristics of the mixture 101 can be distinct fromconventional mixtures and gels, such as those described in certainreferences. Moreover, the mixture 101 can be formed to have a particularrelationship between one or more rheological characteristics (e.g.,viscosity, yield stress, storage modulus, etc.) to facilitate forming.Notably, the gel may be significantly more “stiff”, having a shearthinning characteristic, which may be entirely distinct from mixturesused in other forming methods.

Moreover, the mixture 101 can be formed to have a particular content oforganic materials, including for example, organic additives that can bedistinct from the liquid, to facilitate processing and formation ofshaped abrasive particles according to the embodiments herein. Somesuitable organic additives can include stabilizers, binders, such asfructose, sucrose, lactose, glucose, UV curable resins, and the like. Itwill be appreciated that the total content of all materials in themixture (e.g., ceramic powder material, water, additives, etc.) add upto and do not exceed 100%.

Notably, the embodiments herein may utilize a mixture 101 that can bedistinct from certain types of slurries. For example, the content oforganic materials within the mixture 101, particularly, any of theorganic additives noted above may be a minor amount as compared to othercomponents within the mixture 101. In at least one embodiment, themixture 101 can be formed to have not greater than about 30 wt % organicmaterial for the total weight of the mixture 101. In other instances,the amount of organic materials may be less, such as not greater thanabout 15 wt %, not greater than about 10 wt %, or even not greater thanabout 5 wt %. Still, in at least one non-limiting embodiment, the amountof organic materials within the mixture 101 can be at least about 0.5 wt% for the total weight of the mixture 101. It will be appreciated thatthe amount of organic materials in the mixture 101 can be within a rangebetween any of the minimum and maximum values noted above. In at leastone alternative aspect, the mixture 101 may be essentially free oforganic material.

Moreover, the mixture 101 can be formed to have a particular content ofacid or base distinct from the liquid, to facilitate processing andformation of shaped abrasive particles according to the embodimentsherein. Some suitable acids or bases can include nitric acid, sulfuricacid, citric acid, hydrochloric acid, tartaric acid, phosphoric acid,ammonium nitrate, and/or ammonium citrate. According to one particularembodiment, the mixture 101 can have a pH of less than about 5, and moreparticularly, within a range between at least about 2 and not greaterthan about 4, using a nitric acid additive. Alternatively, the rheologyof the acidic gel can be further modified by converting the acidic gelto a basic gel through the use of bases such as ammonium hydroxide,sodium hydroxide, organics amines such as hexamethylenetetramine and thelike

Referencing FIG. 1, the mixture 101 can be provided within the interiorof the die 103 and configured to be extruded through a die opening 105positioned at one end of the die 103. As further illustrated, extrudingcan include applying a force 180 (or a pressure) on the mixture 101 tofacilitate extruding the mixture 101 through the die opening 105. Inaccordance with an embodiment, a particular pressure may be utilizedduring extrusion. For example, the pressure can be at least about 10kPa, such as at least about 500 kPa, at least about 1,000 kPa, at leastabout 2,000 kPa, or even at least about 3,000 kPa. Still, in at leastone non-limiting embodiment, the pressure utilized during extrusion canbe not greater than about 10,000 kPa, such as not greater than about8,000 kPa, or even not greater than about 6,000 kPa. It will beappreciated that the pressure used to extrude the mixture 101 can bewithin a range between any of the minimum and maximum values notedabove. Moreover, in certain instances, the die opening can have an areaof approximately 3000 to 4000 square millimeters.

In accordance with one embodiment, the mixture 101 can have a coil valueof at least about 1800 N. The coil value can be measured on aninstrument called a Shimpo compression tester manufactured by ShimpoInstruments, Itasca Ill., using a sample of mixture ranging from 30-60grams in mass, which is manually pressed into a plastic/stainless steelcylinder of 2″ in diameter. At the extrusion end of the cylinder, aplastic insert with a cylindrical hole establishes the compressedextrudate size of generally 2 mm in diameter. A plunger slides into thecylinder and when the test is started, the plunger will extrude the gelonce the threshold coil force is reached. When the cylinder assembly isin position, the Shimpo compression tester moves a force probe downtowards the plunger at a constant rate of 95-97 mm/min. When thethreshold coil force is reached, the gel is extruded out of the inserthole and an output meter generates a peak force, which is the coilvalue. In another embodiment, the coil value can be at least about 1900N, such as at least about 2000 N, at least about 2100 N, at least about2200 N, or even at least about 2300 N. In one non-limiting embodiment,the coil value can be not greater than about 8000 N, such as not greaterthan about 6000 N, or even not greater than about 5000 N. Typically,coil values utilized for mixtures and gels used in conventional screenprinting and molding processes, such as the processes described in U.S.Pat. Nos. 5,201,916 and 6,054,093 are less than about 1700 N, and moretypically around 1000 N. Thus, certain mixtures according to theembodiments herein can be significantly more flow resistant compared toconventional mixtures.

As further illustrated in FIG. 1, the system 100 can include a shapingassembly 151. The shaping assembly can include a first portion 152 and asecond portion 153. Notably, within the applications zone 183, the firstportion 152 can be adjacent to the second portion 153. In moreparticular instances, within the application zone 183, the first portion152 can be abutting a surface 157 of the second portion 153. The system100 can be designed such that a portion of the shaping assembly 151,such as the first portion 152, may be translated between rollers. Thefirst portion 152 may be operated in a loop such that the formingprocess can be conducted continuously.

As illustrated, the system 100 can include an application zone 183,including the die opening 105 of the die 103. The process can furtherinclude applying the mixture 101 into at least a portion of the shapingassembly 151. In particular instances, the process of applying themixture 101 can include depositing the mixture 101 via a process, suchas, extrusion, molding, casting, printing, spraying, and a combinationthereof. In particular instances, such as that illustrated in FIG. 1,the mixture 101 may be extruded in a direction 188 through the dieopening 105 and into at least a portion of the shaping assembly 151.Notably, a least a portion of the shaping assembly 151 can include atleast one opening 154. In particular instances, such as that illustratedin FIG. 1, the shaping assembly 151 can include a first portion 152having an opening 154 configured to receive the mixture 101 from the die103.

In accordance with an embodiment, the shaping assembly 151 can includeat least one opening 154 that can be defined by a surface or multiplesurfaces, including for example, at least three surfaces. In particularinstances, the opening 154 can extend through an entire thickness of thefirst portion 152 of the shaping assembly 151. Alternatively, theopening 154 can extend through an entire thickness of the shapingassembly 151. Still, in other alternative embodiments, the opening 154can extend through a portion of the entire thickness of the shapingassembly 151.

Referring briefly to FIG. 2, a segment of a first portion 152 isillustrated. As shown, the first portion 152 can include an opening 154,and more particularly, a plurality of openings 154. The openings 154 canextend into the volume of the first portion 152, and more particularly,extend through the entire thickness of the first portion 152 asperforations. As further illustrated, the first portion 152 of theshaping assembly 151 can include a plurality of openings 154 displacedfrom each other along a length of the first portion 152. In particularinstances, the first portion 152 may be translated in a direction 186through the application zone 183 at a particular angle relative to thedirection of extrusion 188. In accordance with an embodiment, the anglebetween the directions of translation 186 of the first portion 152 andthe direction of extrusion 188 can be substantially orthogonal (i.e.,substantially 90°). However, in other embodiments, the angle may bedifferent, such as acute, or alternatively, obtuse.

In particular instances, the shaping assembly 151 can include a firstportion 152 that may be in the form of a screen, which may be in theform of a perforated sheet. Notably, the screen configuration of thefirst portion 152 may be defined by a length of material having aplurality of openings 154 extending along its length and configured toaccept the mixture 101 as it is deposited from the die 103. The firstportion can be in the form of a continuous belt that is moved overrollers for continuous processing. In certain instances, the belt can beformed to have a length suitable for continuous processing, includingfor example, at length of at least about 0.1 m, such as at least about0.5 m. Still, in another embodiment, the length of the belt may not needto be particularly long to facilitate efficient and productiveprocessing. For example, in one non-limiting embodiment, the belt may beless than about 10 m, not greater than about 8 m, not greater than about5 m, not greater than about 3 m, not greater than about 2 m, or even notgreater than about 1 m.

In a particular instance, the openings 154 can have a two-dimensionalshape as viewed in a plane defined by the length (l) and width (w) ofthe screen. While the openings 154 are illustrated as having atriangular two-dimensional shape, other shapes are contemplated. Forexample, the openings 154 can have a two-dimensional shape such aspolygons, ellipsoids, numerals, Greek alphabet letters, Latin alphabetletters, Russian alphabet characters, Arabic alphabet characters (oralphabet letters of any language), complex shapes including acombination of polygonal shapes, and a combination thereof. Inparticular instances, the openings 154 may have two-dimensionalpolygonal shapes such as, a triangle, a rectangle, a quadrilateral, apentagon, a hexagon, a heptagon, an octagon, a nonagon, a decagon, and acombination thereof. Moreover, a first portion 152 can be formed toinclude a combination of openings 154 having a plurality of differenttwo-dimensional shapes. It will be appreciated that the first portion152 may be formed to have a plurality of openings 154 that may havedifferent two-dimensional shapes as compared to each other.

In other embodiments, the shaping assembly 151 may be in the form of amold. In particular, the shaping assembly 151 can be in the shape of amold having openings 154 defining side surfaces and a bottom surfaceconfigured to accept the mixture 101 from the die 103. Notably, a moldconfiguration may be distinct from a screen configuration such that themold has openings that do not extend through the entire thickness of theshaping assembly 151.

In one design, the shaping assembly 151 can include a second portion 153configured to be adjacent to the first portion 152 within theapplication zone 183. In particular instances, the mixture 101 can beapplied into the opening 154 of the first portion 152 and configured toabut a surface 157 of the second portion 153 within the application zone183. For one particular design, the second portion 153 can be configuredas a stop surface allowing the mixture 101 to fill the opening 154within the first portion 152.

According to one embodiment, the surface 154 of the second portion 153can be configured to contact the mixture 101 while it is containedwithin the opening 154 of the first portion 152. The surface 157 mayhave a particular coating to facilitate processing. For example, thesurface 157 may include a coating including an inorganic material, anorganic material, and a combination thereof. Some suitable inorganicmaterials can include a ceramic, a glass, a metal, a metal alloy, and acombination thereof. Certain suitable examples of an inorganic materialcan include a polymer, including for example, a fluoropolymer, such aspolytetrafluoroethylene (PTFE).

Alternatively, the surface 157 may include features, including forexample protrusions and grooves such that during processing the mixture101 contained within the opening 154 of the first portion 152 mayreplicate features contained on the surface 157 of the second portion153.

In an alternative embodiment, the second portion 153, and moreparticularly the surface 157 of the second portion 153 may include aspecific composition that may be imparted to the mixture 101 containedin the opening 154 of the first portion 152. For example, the surface157 may be coated with an additive. The additive may be an inorganicmaterial, organic material, and a combination thereof. In certaininstances, the additive may be a dopant. In such embodiments, thesurface of the mixture 101 in contact with the surface 157 of the secondportion 153 may be doped while it is contained in the shaping assembly151, and more particularly, within the opening 154 of the first portion152.

As described herein, in particular instances, the first portion 152 maybe translated in a direction 186. As such, within the application on183, the mixture 101 contained in the openings 154 of the first portion152 may be translated over the surface 157 of the second portion 153. Inaccordance with an embodiment, the first portion 152 may be translatedin a direction 186 at a particular rate to facilitate suitableprocessing. For example, the first portion 152 may be translated throughthe application zone 183 at a rate of at least about 0.5 mm/s. In otherembodiments, the rate of translation of the first portion 152 may begreater, such as at least about 1 cm/s, at least about 3 cm/s, at leastabout 4 cm/s, at least about 6 cm/s, at least about 8 cm/s, or even atleast about 10 cm/s. Still, in at least one non-limiting embodiment, thefirst portion 152 may be translated in a direction 186 at a rate of notgreater than about 5 m/s, such as not greater than about 1 m/s, or evennot greater than about 0.5 m/s. It will be appreciated that the firstportion 152 may be translated at a rate within a range between any ofthe minimum and maximum values noted above.

After applying the mixture 101 in the openings 154 of the first portion152 of the shaping assembly 151, the first portion 152 may be translatedto an ejection zone 185. Translation may be facilitated by a translatorconfigured to translate at least a portion of the shaping assembly fromthe application zone 183 to the ejection zone 185. Some suitableexamples of a translator may include a series of rollers, about whichthe first portion 152 may be looped and rotated around.

The ejection zone may include at least one ejection assembly 187 thatcan be configured to direct an ejection material 189 at the mixture 101contained within the openings 154 of the first portion 152. In aparticular embodiment, during the translation of the first portion 152from the application zone 183 to the ejection zone 185, only a portionof the shaping assembly 151 may be moved. For example, the first portion152 of the shaping assembly 151 may be translated in a direction 186,while at least the second portion 153 of the shaping assembly 151 may bestationary relative to the first portion 152. That is, in particularinstances the second portion 153 may be contained entirely within theapplication zone 183 and may be removed from contact with the firstportion 152 within the ejection zone 185. In particular instances, thesecond portion 153, which in certain embodiments may be alternativelyreferred to as the backing plate, terminates prior to the ejection zone185.

The first portion 152 can be translated from the application zone 183into the ejection zone 185, wherein opposing major surfaces of themixture 101 contained within the openings 154 of the first portion 152may be exposed. In certain instances, exposure of both major surfaces ofthe mixture 101 in the openings 154 can facilitate further processing,including for example, ejection of the mixture 101 from the openings154.

As further illustrated in the assembly 100, in particular embodiments,the first portion 152 of the shaping assembly 151 can be in directcontact with the second portion 153 of the shaping assembly 151 withinthe application zone 183. Moreover, prior to translating the firstportion 152 from the application zone 183 to the ejection zone 185, thefirst portion 152 can be separated from the second portion 153. As such,the mixture 101 contained within the openings 154 can be removed from atleast one surface of a portion of the shaping assembly 151, and moreparticularly, the surface 157 of the second portion 153 of the shapingassembly 151. Notably, the mixture 101 contained within the opening 154can be removed from the surface 157 of the second portion 153 prior toejection of the mixture 101 from the openings 154 in the ejection zone185. The process of removing the mixture 101 from the first portion 152of the shaping assembly 151 can be conducted after removing the secondportion 153 from contact with the first portion 152.

In one embodiment, the ejection material 189 can be directed at thefirst portion 152 of the shaping assembly 151 to facilitate contact withthe mixture 101 in the openings 154 of the first portion 152. Inparticular instances, the ejection material 189 can directly contact anexposed major surface of the mixture 101 and an opening 154 of the firstportion 152 of the shaping assembly 151. As will be appreciated, atleast a portion of the ejection material 189 may also contact a majorsurface of the second portion 152 as it is translated by the ejectionassembly 187.

In accordance with an embodiment, the ejection material 189 can be afluidized material. Suitable examples of fluidized materials can includea liquid, a gas, and a combination thereof. In one embodiment, thefluidized material of the ejection material 189 can include an inertmaterial. Alternatively, the fluidized material can be a reducingmaterial. Still, in another particular embodiment, the fluidizedmaterial may be an oxidizing material. According to one particularembodiment, the fluidized material can include air.

In an alternative embodiment, the ejection material 189 may include anaerosol comprising a gas phase component, a liquid phase component, asolid phase component, and a combination thereof. In yet anotherembodiment, the ejection material 189 can include an additive. Somesuitable examples of additives can include materials such as an organicmaterial, an inorganic material, a gas phase component, a liquid phasecomponent, a solid phase component, and a combination thereof. In oneparticular instance, the additive can be a dopant material configured todope the material of the mixture 101. In accordance with anotherembodiment, the dopant can be a liquid phase component, a gas phasecomponent, a solid phase component, or a combination thereof that can becontained within the ejection material. Still, in one particularinstance, the dopant can be present as a fine powder suspended in theejection material.

Directing the ejection material at the mixture 101 in the opening 154 ofthe first portion 152 of the shaping assembly 151 can be conducted at apredetermined force. The predetermined force may be suitable to ejectthe mixture from the opening 154 to form a precursor shaped abrasiveparticle, and may be a function of the rheological parameters of themixture 101, the geometry of the cavity, the materials of constructionof shaping assembly, surface tension forces between the mixture 101 andthe materials of the shaping assembly 151, and a combination thereof. Inone embodiment, the predetermined force can be at least about 0.1 N,such as at least about 1 N, at least about 10 N, at least about 12 N, atleast about 14 N, at least about 16 N, at least about 50 N, or even atleast about 80 N. Still, in one non-limiting embodiment, thepredetermined force may be not greater than about 500 N, such as notgreater than about 200 N, not greater than about 100 N, or even notgreater than about 50 N. The predetermined force may be within a rangebetween any of the minimum and maximum values noted above.

Notably, the use of the ejection material 189 may be essentiallyresponsible for the removal of the mixture 101 from the opening 154.More generally, the process of removing the mixture 101 from an opening154 can be conducted by applying an external force to the mixture 101.Notably, the process of applying external force includes limited strainof the shaping assembly and an application of an outside force to ejectthe mixture 101 from the opening 154. The process of ejection causesremoval of the mixture 101 from the opening 154 and may be conductedwith relatively little or essentially no shearing of the first portion152 relative to another component (e.g., the second portion 153).Moreover, ejection of the mixture may be accomplished with essentiallyno drying of the mixture 101 within the opening 154. As will beappreciated, the precursor shaped abrasive particle 191 may be ejectedfrom the opening 154 and collected. Some suitable methods of collectingcan include a bin underlying the first portion 152 of the shapingassembly 151. Alternatively, the mixture 101 can be ejected from theopening 154 in such a manner that the precursor shaped abrasive particle191 falls back onto the first portion 152 after ejection. The precursorshaped abrasive particle 191 can be translated out of the ejection zoneon the first portion 152 to other zones for further processing.

In accordance with an embodiment, the mixture 101 can experience achange in weight of less than about 5% for the total weight of themixture 101 for the duration the mixture 101 is in the opening of thefirst portion 152 of the shaping assembly 151. In other embodiments, theweight loss of the mixture 101 while it is contained within the shapingassembly 151 can be less, such as less than about 4%, less than about3%, less than about 2%, less than about 1%, or even less than about0.5%. Still, in one particular embodiment, the mixture 101 may haveessentially no change in weight for the duration the mixture 101 is inthe opening 154 of the shaping assembly 151.

Furthermore, during processing, the mixture 101 may experience a limitedchange in volume (e.g., shrinkage) for the duration the mixture 101 isin an opening 154 of the shaping assembly 151. For example, the changeof volume of the mixture 101 can be less than about 5% for the totalvolume of the mixture 101 for the duration between applying the mixture101 in the opening and ejection of the mixture from the opening 154. Inother embodiments, the total change in volume may be less, such as lessthan about 4%, less than about 3%, less than about 2%, less than about1%, or even less than about 0.5%. In one particular embodiment, themixture may experience essentially no change in volume for the entireduration the mixture 101 is in an opening 154 of the shaping assembly151.

In accordance with an embodiment, the mixture 101 may undergo acontrolled heating process, while the mixture is contained within theshaping assembly 151. For example, the heating process may includeheating the mixture at a temperature greater than room temperature for alimited time. The temperature may be at least about 30° C., such as atleast about 35° C., at least about 40° C., such as at least about 50°C., at least about 60° C., or even at least about 100° C. Still, thetemperature may be not greater than about 300° C., such as not greaterthan about 200° C., or even not greater than about at least about 150°C., or even not greater than about 100° C. The duration of heating canbe particularly short, such as not greater than about 10 minutes, notgreater than about 5 minutes, not greater than about 3 minutes, notgreater than about 2 minutes, or even not greater than about 1 minute.

The heating process may utilize a radiant heat source, such as infraredlamps to facilitate controlled heating of the mixture 101. Moreover, theheating process may be adapted to control the characteristics of themixture and facilitate particular aspects of the shaped abrasiveparticles according to embodiments herein.

Yet, in another aspect, the mixture 101 may undergo a limited change intemperature within the shaping assembly 151, and particularly, thesystem may utilize a limited temperature differential between theapplication zone 183 and the ejection zone 185. For example, the mixture101 can experience a change in temperature of not greater than about 10°C. in a duration between applying the mixture 101 into the shapingassembly 151 and removing the mixture 101 from the shaping assembly 151.In other embodiments, the difference can be less, such as not greaterthan about 8° C., not greater than about 6° C., not greater than about4° C., or even essentially no change in temperature in the duration themixture 101 is contained within the shaping assembly 151.

In certain instances, the method may utilize a particular distancebetween the application zone 183 and the ejection zone 185, and moreparticularly, between the point of filling the shaping assembly 151 withthe mixture 101 and the ejection assembly 187, including for example, atleast about 0.2 m. Still, in other designs, the distance between theapplication zone 183 and ejection zone 185 may be not greater than about10 m, such as not greater than about 1 m. This may facilitate a smallerfootprint of the system and improved productivity.

The method of forming a precursor shaped abrasive particle may beconducted in a rapid fashion facilitating efficient processing. Forexample, the mixture may have an average residence time in an opening154 of the shaping assembly 151 that is less than about 18 minutes. Inother embodiments, the average residence time can be less than about 14minutes, less than about 12 minutes, less than about 10 minutes, lessthan about 8 minutes, less than about 7 minutes, less than about 6minutes, less than about 5 minutes, less than about 2 minutes, less thanabout 1 minute, less than about 50 seconds, less than about 40 seconds,less than about 30 seconds, less than about 20 seconds, or even lessthan about 15 seconds. Still, in at least one non-limiting embodiment,the average residence time can be at least about 1 second. It will beappreciated that the average residence time can be within a rangebetween any of the minimum and maximum times noted above.

In accordance with an embodiment, the process of ejecting the mixture101 from an opening 154 of the shaping assembly 151 can be conducted ata particular temperature. For example, the process of ejection can beconducted at a temperature of not greater than about 300° C. In otherembodiments, the temperature during ejection can be not greater thanabout 250° C., not greater than about 200° C., not greater than about180° C., not greater than about 160° C., not greater than about 140° C.,not greater than about 120° C., not greater than about 100° C., notgreater than about 90° C., not greater than about 60° C., or even notgreater than about 30° C. Alternatively, in a non-limiting embodiment,the process of directing an ejection material at the mixture andejecting the mixture 101 from an opening 151 may be conducted at certaintemperatures, including those temperatures that may be above roomtemperature. Some suitable temperatures for conducting the ejectionprocess can be at least about −80° C., such as at least about −50° C.,at least about −25° C., at least about 0° C., at least about 5° C., atleast about 10° C., or even at least about 15° C. It will be appreciatedthat in certain non-limiting embodiments, the process of ejecting themixture 101 from an opening 154 may be conducted at a temperature withina range between any of the temperatures noted above.

Furthermore, it will be appreciated that the ejection material 189 maybe prepared and ejected from the ejection assembly 187 at apredetermined temperature. For example, the ejection material 189 may beat a temperature significantly less than the surrounding environment,such that upon contact with the mixture 101 within the opening 154, themixture is configured to be reduced in temperature. During the ejectionprocess, the mixture 101 may be contacted by the ejection material 187that can be cooler in temperature than the temperature of the mixture101 causing contraction of the material of the mixture 101 and ejectionfrom the opening 154.

In accordance with an embodiment, the ejection assembly 187 can have aparticular relationship with respect to the openings 154 of the shapingassembly 151 to facilitate suitable formation of precursor shapedabrasive particles according to an embodiment. For example, in certaininstances, the ejection assembly 187 can have an ejection materialopening 176 from which the ejection material 189 exits the ejectionassembly 187. The ejection material opening 176 can define an ejectionmaterial opening width 177. Furthermore, the openings 154 of the firstportion 152 can have a shaping assembly opening width 178 as illustratedin FIG. 1, which may define a largest dimension of the opening in thesame direction as the ejection material opening width 177. In particularinstances, the ejection material opening width 177 can be substantiallythe same as the shaping assembly opening width 178. In still anotherembodiment, the ejection material opening width 177 can be differentthan the shaping assembly opening width 178, such as for example, theejection material opening width 177 can be significantly less than theshaping assembly opening width 178. According to one particularembodiment, the ejection material opening width 177 can be not greaterthan about 50% of the shaping opening width 178. In yet anotherembodiment, the ejection material opening width 177 can be not greaterthan about 40%, such as not greater than about 30%, not greater thanabout 20%, not greater than about 10%, not greater than about 8%, notgreater than about 6%, not greater than about 5%, not greater than about4%, not greater than about 3%, or even not greater than about 2% of theshaping opening width 178. Still, in at least one non-limitingembodiment, the ejection material opening width 177 can be at leastabout 0.01%, such as at least about 178.

Moreover, the gap distance 173 between the surface of the ejectionassembly 187 and the first portion 152 of the shaping assembly can becontrolled to facilitate formation of shaped abrasive particlesaccording to an embodiment. The gap distance 173 may be modified tofacilitate forming shaped abrasive particles with certain features orlimiting the formation of certain features.

It will further be appreciated that a pressure differential may becreated on opposite sides of the first portion 152 of the shapingassembly 151 within the ejection zone 185. In particular, in addition touse of the ejection assembly 187, the system 100 may utilize an optionalsystem 179 (e.g., a reduced pressure system) configured to reduce thepressure on the opposite side of the first portion 152 from the ejectionassembly 187 to facilitate pulling the precursor shaped abrasiveparticle 191 from the opening 154. The process may include providing anegative pressure difference on the side of the shaping assemblyopposite the ejection assembly 187. It will be appreciated thatbalancing the predetermined force of the ejection material and thenegative pressure applied to the back side 172 of the first portion 152of the shaping assembly within the ejection zone 185 can facilitateformation of different shape features in the precursor shaped abrasiveparticles 191 and the final-formed shaped abrasive particles.

After ejecting the mixture 101 from the opening 154 of the first portion152, a precursor shaped abrasive particle is formed. According to aparticular embodiment, the precursor shaped abrasive particle can have ashape substantially replicating the shape of the openings 154.

The system and methods of the embodiments herein may have a particularefficiency and productivity associated with forming precursor shapedabrasive particles. In one particular instance, the method can includeforming a batch of precursor shaped abrasive particles having a weightof not less than about 1 kg in not greater than about 30 minutes. In yetanother embodiment, the system and the method of forming can beconfigured to have a batch efficiency of at least about 0.05 kg/min,such as at least about 0.07 kg/min, at least about 0.08 kg/min, at leastabout 0.09 kg/min, at least about 0.1 kg/min, at least about 0.13kg/min, at least about 0.15 kg/min, such as at least about 0.17 kg/min,at least about 0.2 kg/min, at least about 0.3 kg/min, at least about 0.4kg/min, at least about 0.5 kg/min, at least about 0.6 kg/min, or even atleast about 0.8 kg/min.

The system and method of the embodiments herein may have a particularproductivity associated with forming precursor shaped abrasiveparticles. In one particular instance, the system can be configured tohave a batch productivity of at least about 0.1 kg/min/m² of shapingsurface, wherein the area of the shaping surface is the total surfacearea of a single side of the first portion (including openings), whichmay be in the form of a belt. In another embodiment, the system can havea batch productivity of at least about 0.15 kg/min/m², at least about0.2 kg/min/m², at least about 0.25 kg/min/m², at least about 0.3kg/min/m², at least about 0.35 kg/min/m², at least about 0.4 kg/min/m²,such as at least about 0.45 kg/min/m², at least about 0.5 kg/min/m², atleast about 0.55 kg/min/m², at least about 0.6 kg/min/m², at least about0.7 kg/min/m², at least about 0.8 kg/min/m², or even at least about 1kg/min/m².

In certain instances, the precursor shaped abrasive particle can begathered and undergo further processing. For example, further processingcan include shaping, applying a dopant material, drying, sintering, andthe like. In fact, the precursor shaped abrasive particle may betranslated through a shaping zone, wherein at least one exterior surfaceof the particles may be shaped. Shaping can include altering a contourof the precursor shaped abrasive particle through one or more processes,such as, embossing, rolling, cutting, engraving, patterning, stretching,twisting, and a combination thereof. In one particular embodiment, theprocess of shaping can include contacting a shaping structure, having aparticular texture to an exterior surface of the precursor shapedabrasive particle to impart the texture to the exterior surface of theparticle. It will be appreciated that the shaping structure can takevarious forms, including for example, a roller having various featureson its surface.

In certain other instances, after ejection, the precursor shapedabrasive particle may have a dopant material applied to at least oneexterior surface of the precursor particle. A dopant material may beapplied utilizing various methods including for example, spraying,dipping, depositing, impregnating, transferring, punching, cutting,pressing, crushing, and any combination thereof. In particularinstances, the application zone may utilize a spray nozzle, or acombination of spray nozzles to spray dopant material onto the precursorshaped abrasive particle. It will be appreciated that the process ofapplying a dopant material during further processing can be performed atvarious processing stages, including for example, before drying or afterdrying, or before calcining or after calcining, before sintering orafter sintering.

In accordance with an embodiment, applying a dopant material can includethe application of a particular material, such as a salt, which can be aprecursor salt material that includes a dopant material to beincorporated into the finally-formed shaped abrasive particles. Forexample, a metal salt can include an element or compound that is thedopant material. It will be appreciated that the salt material may be inliquid form, such as in a dispersion comprising the salt and liquidcarrier. The salt may include nitrogen, and more particularly, caninclude a nitrate. In one embodiment, the salt can include a metalnitrate, and more particularly, consist essentially of a metal nitrate.

In one embodiment, the dopant material can include an element orcompound such as an alkali element, alkaline earth element, rare earthelement, hafnium, zirconium, niobium, tantalum, molybdenum, vanadium, ora combination thereof. In one particular embodiment, the dopant materialincludes an element or compound including an element such as lithium,sodium, potassium, magnesium, calcium, strontium, barium, scandium,yttrium, lanthanum, cesium, praseodymium, niobium, hafnium, zirconium,tantalum, molybdenum, vanadium, chromium, cobalt, iron, germanium,manganese, nickel, titanium, zinc, silicon, boron, carbon and acombination thereof.

And further, the precursor shaped abrasive particle may undergo furtherprocessing, including for example, heating, curing, vibration,impregnation, and a combination thereof. In one embodiment, theprecursor shaped abrasive particle may be dried. Drying may includeremoval of a particular content of material, including volatiles, suchas water. In accordance with an embodiment, the drying process can beconducted at a drying temperature of not greater than about 300° C.,such as not greater than about 280° C., or even not greater than about250° C. Still, in one non-limiting embodiment, the drying process may beconducted at a drying temperature of at least about 10° C. It will beappreciated that the drying temperature may be within a range betweenany of the minimum and maximum temperatures noted above.

In accordance with an embodiment, the process of forming the shapedabrasive particle may include additional processes, includingcalcination, impregnation, sintering and a combination thereof.Calcination may occur to remove volatiles and cause a phase change inthe material, including for example, a high-temperature phase material(e.g., alpha alumina). In one instance, a shaped abrasive particle cancomprise at least about 80 wt % alpha alumina for the total weight ofthe particle. In other instances, the content of alpha alumina may begreater, such that the shaped abrasive particle may consist essentiallyof alpha alumina. Impregnation may occur to incorporate other materialsinto the material of the mixture 101, including for example, a dopant.Sintering of the precursor shaped abrasive particle may be utilized todensify the particle. In a particular instance, the sintering processcan facilitate the formation of a high-temperature phase ceramicmaterial. For example, in one embodiment, the precursor shaped abrasiveparticle may be sintered such that a high-temperature phase of alumina,such as alpha alumina is formed.

Additional processes, such as cleaning, may be completed on any portionsof the shaping assembly 151, to facilitate regular and repetitiveprocessing. For example, cleaning may be conducted on the first portion152 after ejecting the mixture, and more particularly cleaning theopenings 154 of the first portion 152 after translating the firstportion 152 through the ejection zone 185. Additionally, the portions ofthe shaping assembly 151, may undergo a drying process.

After the precursor shaped abrasive particle is sintered, afinally-formed shaped abrasive particle results, which may beincorporated into an abrasive tool, including for example, a coatedabrasive, a bonded abrasive, and the like. According to one embodiment,the shaped abrasive particle can have a particular size, as measured bythe length of the body. For example, the shaped abrasive particle mayhave a median particle size of not greater than about 5 mm.Alternatively, the median particle may be less, such as not greater thanabout 4 mm, not greater than about 3 mm, not greater than about 2 mm, oreven not greater than about 1.5 mm. In still another aspect, the medianparticle size of the shaped abrasive particle can be at least about 10microns, at least about 100 microns, at least about 200 microns, atleast about 400 microns, at least about 600 microns, or even at leastabout 800 microns. It will be appreciated that the median particle sizeof the shaped abrasive particle can be within a range between any of theabove minimum and maximum values.

The shaped abrasive particle of one embodiment can have a particulargrain size, particularly for grains of alpha alumina. For example, theshaped abrasive particle may have an average grain size of not greaterthan about 500 microns, such as not greater than about 250 microns, oreven not greater than about 100 microns, not greater than about 50microns, not greater than about 20 microns, or even not greater thanabout 1 micron. In another aspect, the average grain size can be atleast about 0.01 microns, such as at least about 0.05 microns, at leastabout 0.08 microns, or even at least about 0.1 microns. It will beappreciated that the average grain size of the shaped abrasive particlecan be within a range between any of the above minimum and maximumvalues.

In yet another embodiment, the shaped abrasive particle can include adopant material, which can include an element or compound such as analkali element, alkaline earth element, rare earth element, hafnium,zirconium, niobium, tantalum, molybdenum, vanadium, or a combinationthereof. In one particular embodiment, the dopant material includes anelement or compound including an element such as lithium, sodium,potassium, magnesium, calcium, strontium, barium, scandium, yttrium,lanthanum, cesium, praseodymium, niobium, hafnium, zirconium, tantalum,molybdenum, vanadium, silicon, boron, carbon or a combination thereof.

In certain instances, the shaped abrasive particle can be formed to havea specific content of dopant material. For example, the body of a shapedabrasive particle may include not greater than about 20 wt % dopantmaterial for the total weight of the body. In other instances, theamount of dopant material can be less, such as not greater than about 16wt %, not greater than about 14 wt %, not greater than about 12 wt %,not greater than about 11 wt %, not greater than about 10 wt %, notgreater than about 9 wt %, not greater than about 8 wt %, not greaterthan about 7 wt %, not greater than about 6 wt %, or even not greaterthan about 5 wt % for the total weight of the body. In at least onenon-limiting embodiment, the amount of dopant material can be at leastabout 0.5 wt %, such at least about 1 wt %, at least about 1.3 wt %, atleast about 1.8 wt %, at least about 2 wt %, at least about 2.3 wt %, atleast about 2.8 wt %, or even at least about 3 wt % for the total weightof the body. It will be appreciated that the amount of dopant materialwithin the body of the shaped abrasive particle can be within a rangebetween any of the minimum or maximum percentages noted above.

A shaped abrasive particle according to one embodiment can have a bodydefined by a length (l), which can be the longest dimension of any sideof the shaped abrasive particle, a width (w) defined as a longestdimension of the shaped abrasive particle through a midpoint of theshaped abrasive particle, and a thickness (t) defined as the shortestdimension of the shaped abrasive particle extending in a directionperpendicular to the length and width. In specific instances, the lengthcan be greater than or equal to the width. Moreover, the width can begreater than or equal to the thickness.

Additionally, the body of the shaped abrasive particle can haveparticular two-dimensional shapes. For example, the body can have atwo-dimensional shape as viewed in a plane define by the length andwidth having a polygonal shape, ellipsoidal shape, a numeral, a Greekalphabet character, Latin alphabet character, Russian alphabetcharacter, or any alphabet character, complex shapes utilizing acombination of polygonal shapes and a combination thereof. Particularpolygonal shapes include triangular, rectangular, quadrilateral,pentagon, hexagon, heptagon, octagon, nonagon, decagon, any combinationthereof.

FIGS. 3A-3C include perspective view illustrations of shaped abrasiveparticles that can be formed through the processes of the embodimentsherein. FIG. 3A includes a perspective view illustration of a shapedabrasive particle in accordance with an embodiment. In particular, thebody 301 of the shaped abrasive particle can have a length (l), a width(w) extending through a midpoint 302 of the body 301, and a thickness(t). In accordance with an embodiment, the body 301 can have a primaryaspect ratio defined as a ratio of length:width. In certain instances,the primary aspect ratio of the body 301 can be at least about 1.2:1,such as at least about 1.5:1, at least about 2:1, at least about 3:1, oreven at least about 4:1. Still, the primary aspect ratio may be notgreater than about 100:1. It will be appreciated that the primary aspectratio of the body 301 may be within a range between any of the minimumand maximum ratios noted above.

Furthermore, the body 301 can have a secondary aspect ratio defined by aratio of length:thickness. In certain instances, the secondary aspectratio of the body 301 may be at least about 1.2:1, such as at leastabout 1.5:1, at least about 2:1, at least about 3:1, at least about 4:1,at least about 5:1, or even at least about 10:1. Still, in at least onenon-limiting embodiment, the body 301 can have a secondary aspect ratiothat is not greater than about 100:1. It will be appreciated that thesecondary aspect ratio may be within a range between any of the minimumand maximum ratios provided above.

Furthermore, the shaped abrasive particle of an embodiment can have atertiary aspect ratio defined by a ratio of the width:thickness. Incertain instances, the tertiary aspect ratio of the body 301 may be atleast about 1.2:1, such as at least about 1.5:1, at least about 2:1, atleast about 3:1, at least about 4:1, at least about 5:1, or even atleast about 10:1. Still, in at least one non-limiting embodiment, thebody 301 can have a tertiary aspect ratio that is not greater than about100:1. It will be appreciated that the tertiary aspect ratio may bewithin a range between any of the minimum and maximum ratios providedabove.

FIG. 3B includes a perspective view illustration of a shaped abrasiveparticle in accordance with an embodiment. As illustrated, the shapedabrasive particle can have a corner-truncated triangular shape, whereintwo edges and a side surface extending between the edges replace aposition that would normally be occupied by a single corner in a typicaltriangular-shaped body. In particular, the body 301 of the shapedabrasive particle can have a length (l), a width (w) extending through amidpoint 302 of the body 301, and a thickness (t).

FIG. 3C includes a perspective view illustration of a shaped abrasiveparticle formed in accordance with an embodiment. Notably, the body 301can have a generally quadrilateral shape. However, in one particularembodiment, the body 301 may be a corner truncated quadrilateral, andmore particularly a corner truncated parallelogram or trapazoidal shape,wherein two edges and a side surface extending between the edges replacea position that would normally be occupied by a single corner in atypical quadrilateral-shaped body. In particular, the body 301 of theshaped abrasive particle can have a length (l), a width (w) extendingthrough a midpoint 302 of the body 301, and a thickness (t). The body301 can have the any of the features of any shaped abrasive particledescribed in the embodiments herein.

FIG. 4 includes a cross-sectional illustration of a coated abrasivearticle incorporating the abrasive particulate material in accordancewith an embodiment. As illustrated, the coated abrasive 400 can includea substrate 401 and a make coat 403 overlying a surface of the substrate401. The coated abrasive 400 can further include abrasive particulatematerial 406. The abrasive particulate material 406 can include a firsttype of particles including shaped abrasive particles 405 and a secondtype of abrasive particulate material 407 in the form of diluentabrasive particles. The diluent abrasive particles can have a randomshape, and may not necessarily be shaped abrasive particles. The coatedabrasive 400 may further include size coat 404 overlying and bonded tothe abrasive particulate material 406 and the make coat 404.

According to one embodiment, the substrate 401 can include an organicmaterial, inorganic material, and a combination thereof. In certaininstances, the substrate 401 can include a woven material. However, thesubstrate 401 may be made of a non-woven material. Particularly suitablesubstrate materials can include organic materials, including polymers,and particularly, polyester, polyurethane, polypropylene, polyimidessuch as KAPTON from DuPont, or paper. Some suitable inorganic materialscan include metals, metal alloys, and particularly, foils of copper,aluminum, steel, and a combination thereof.

The make coat 403 can be applied to the surface of the substrate 401 ina single process, or alternatively, the abrasive particulate material406 can be combined with a make coat 403 material and applied as amixture to the surface of the substrate 401. Suitable materials of themake coat 403 can include organic materials, particularly polymericmaterials, including for example, polyesters, epoxy resins,polyurethanes, polyamides, polyacrylates, polymethacrylates, poly vinylchlorides, polyethylene, polysiloxane, silicones, cellulose acetates,nitrocellulose, natural rubber, starch, shellac, and mixtures thereof.In one embodiment, the make coat 403 can include a polyester resin. Thecoated substrate can then be heated in order to cure the resin and theabrasive particulate material to the substrate. In general, the coatedsubstrate 401 can be heated to a temperature of between about 100° C. toless than about 250° C. during this curing process.

The abrasive particulate material 406 can include shaped abrasiveparticles according to embodiments herein. In particular instances, theabrasive particulate material 406 may include different types of shapedabrasive particles. The different types of shaped abrasive particles candiffer from each other in composition, two-dimensional shape,three-dimensional shape, size, and a combination thereof as described inthe embodiments herein. As illustrated, the coated abrasive 400 caninclude a shaped abrasive particle 405 having a generally triangulartwo-dimensional shape.

The other type of abrasive particles 407 can be diluent particlesdifferent than the shaped abrasive particles 405. For example, thediluent particles can differ from the shaped abrasive particles 405 incomposition, two-dimensional shape, three-dimensional shape, size, and acombination thereof. For example, the abrasive particles 407 canrepresent conventional, crushed abrasive grit having random shapes. Theabrasive particles 407 may have a median particle size less than themedian particle size of the shaped abrasive particles 405.

After sufficiently forming the make coat 403 and the abrasiveparticulate material 406, the size coat 404 can be formed to overlie andbond the abrasive particulate material 406 in place. The size coat 404can include an organic material, may be made essentially of a polymericmaterial, and notably, can use polyesters, epoxy resins, polyurethanes,polyamides, polyacrylates, polymethacrylates, poly vinyl chlorides,polyethylene, polysiloxane, silicones, cellulose acetates,nitrocellulose, natural rubber, starch, shellac, and mixtures thereof.

FIG. 5 includes an illustration of a bonded abrasive articleincorporating the abrasive particulate material in accordance with anembodiment. As illustrated, the bonded abrasive 500 can include a bondmaterial 501, abrasive particulate material 502 contained in the bondmaterial, and porosity 508 within the bond material 501. In particularinstances, the bond material 501 can include an organic material,inorganic material, and a combination thereof. Suitable organicmaterials can include polymers, such as epoxies, resins, thermosets,thermoplastics, polyimides, polyamides, and a combination thereof.Certain suitable inorganic materials can include metals, metal alloys,vitreous phase materials, crystalline phase materials, ceramics, and acombination thereof.

In some instances, the abrasive particulate material 502 of the bondedabrasive 500 can include shaped abrasive particles 503, 504, 505, and506. In particular instances, the shaped abrasive particles 503, 504,505, and 506 can be different types of particles, which can differ fromeach other in composition, two-dimensional shape, three-dimensionalshape, size, and a combination thereof as described in the embodimentsherein. Alternatively, the bonded abrasive article can include a singletype of shaped abrasive particle.

The bonded abrasive 500 can include a type of abrasive particulatematerial 507 representing diluent abrasive particles, which can differfrom the shaped abrasive particles 503, 504, 505, and 506 incomposition, two-dimensional shape, three-dimensional shape, size, and acombination thereof.

The porosity 508 of the bonded abrasive 500 can be open porosity, closedporosity, and a combination thereof. The porosity 508 may be present ina majority amount (vol %) based on the total volume of the body of thebonded abrasive 500. Alternatively, the porosity 508 can be present in aminor amount (vol %) based on the total volume of the body of the bondedabrasive 500. The bond material 501 may be present in a majority amount(vol %) based on the total volume of the body of the bonded abrasive500. Alternatively, the bond material 501 can be present in a minoramount (vol %) based on the total volume of the body of the bondedabrasive 500. Additionally, abrasive particulate material 502 can bepresent in a majority amount (vol %) based on the total volume of thebody of the bonded abrasive 500. Alternatively, the abrasive particulatematerial 502 can be present in a minor amount (vol %) based on the totalvolume of the body of the bonded abrasive 500.

According to one aspect, the system and method herein may facilitate theformation of shaped abrasive particles having certain features. Forexample, in one embodiment, a shaped abrasive particle can include abody having a tortuous contour, which may be facilitated by particularaspects of the forming process. In particular instances, the tortuouscontour can include a first curved portion, a second curved portion, anda planar portion joining the first curved portion and the second curvedportion. FIG. 6 includes a side view (inverted color) image of a shapedabrasive particle made according to an embodiment herein. The shapedabrasive particle 600 can include a body 601 having a first majorsurface 603, a second major surface 604, and a side surface 605extending between and separating the first major surface 603 and thesecond major surface 604. In particular, and in accordance with anembodiment, the first major surface 603 can have a tortuous contour,which may include a first curved portion 606, a second curved portion608, and a substantially planar or linear region 607 connecting andextending between the first curved portion 606 and the second curvedportion 608. In one particular embodiment, the first curved portion 606may define a substantially arcuate curvature, which may include asubstantially convex curvature. The second curved portion 608 can bespaced apart from the first curved portion 606 and define asubstantially arcuate curvature, and particularly, a substantiallyconcave portion.

In certain embodiments, such as illustrated in FIG. 6 the first curvedportion 606 can define a first radius of curvature and the second curvedportion 608 can define a second radius of curvature according to aportion of the curve best fit to a circle. Such analysis may becompleted using imaging software, such as ImageJ. In one embodiment, thefirst curved portion 606 and the second curved portion 608 can havedifferent radiuses of curvatures compared to each other. In stillanother embodiment, the radius of curvatures associated with the firstcurved portion 606 and second curved portion 608 may be substantiallysimilar. Moreover, in another particular embodiment, it has beenobserved that the tortuous contour of the first major surface 603 caninclude a first curved portion 606 having a radius of curvature that isgreater than an average height of the body 601, wherein the height canbe measured as the average distance between the first major surface 603and second major surface 604. Additionally, in another embodiment, ithas been observed that the tortuous contour of the first major surface604 can include a second curved portion 608 having a radius of curvaturethat is greater than the average height of the body 601.

In accordance with one particular embodiment, the tortuous contour caninclude a particular waviness. The waviness can be defined as a portionof any surface having the tortuous contour including a first curvedportion extending above a line and further comprising a second curvedportion extending below the line. Referring again to FIG. 6, a line 610is drawn between the corners of the first major surface 603 and the sidesurface 605 of the body 601. In some instances, the line 610 may beparallel to the opposing major surface if the opposite major surfacedefines a substantially planar surface, such as the second major surface604 of the body 601 shown in FIG. 6. As illustrated, the first majorsurface can have a tortuous contour including a waviness, wherein thefirst curved portion 606 includes a region of the first major surface603 that extends on one side (i.e., below in the orientationillustrated) and the second curved portion 608 includes a region of thefirst major surface 603 that extends on the opposite side (i.e., abovein the orientation illustrated) of the line 610 relative to the regionof the first major portion 606.

In a particular embodiment, the curved portions can define a peak heightor valley height depending on the relationship of the curved portions606 and 608 relative to the line 610. The peak height can be thegreatest distance between a point within the curved portion and the line610. For example, the second curved portion 608 can have a peak height620 as the greatest distance between a point on the first major surface602 within the second curved portion 608 and the line 610, in adirection perpendicular to the line and generally extending in thedirection of the height of the particle as viewed from the side.According to one embodiment, the peak height 620 can be at least about5% of an average height of the body 601. In other instances, it can begreater, such as at least about 10%, at least about 15%, at least about20%, at least about 25%, at least about 30%, at least about 35%, atleast about 40%, or even at least about 50%. In still anothernon-limiting embodiment, the peak height 620 can be less than about150%, such as less than about 90% of the average height of the particle.It will be appreciated that the peak height can be within a rangebetween any of the above minimum and maximum percentages.

Moreover, while not illustrated, the first curved portion 606 can definea valley height, as the maximum distance between the line 610 and aportion of the first major surface 603 within the first curved portion606. The valley height can have the same features as the peak height 620associated with the second curved portion 608.

In another embodiment, the tortuous contour can be defined by a portionof the body wherein a slope of a trace line extending along the tortuouscontour changes slope from a region defining a positive slope of thetrace line, to a slope of zero, to a negative slope. For example,referring to FIG. 6, a trace line 612 can be formed along the tortuoussurface and define a first region 613 having a positive slope, a region614 including a slope of zero, and a region wherein the slope of thetrace line 612 changes to a negative value. It will be appreciated thata tortuous surface can include additional changes in slope, includingfor example, an additional transition to a region having a slope ofzero, and a transition to a region having a positive or negative slope.Such characteristics may be defined generally as a sinusoidal-likecurve, which is not to be interpreted as requiring the trace line 612 tocomply with the exact mathematical formula of a sine wave function, butrather as a description of the approximate change in curvature of thetrace line 612.

Notably, as illustrated in the embodiment of FIG. 6, the tortuouscontour can extend along a first major surface 603 of the body 601.However, it will be appreciated that in other embodiments, the tortuouscontour may extend along other surfaces of the body 601, including, butnot limited to, the second major surface 604 and the side surface 605.Moreover, it will be appreciated that more than one surface of the body601 of a shaped abrasive particle according to embodiments herein canexhibit a tortuous contour.

The tortuous contour can extend along at least a portion of any surfaceof the body 601. In particular instances, the tortuous contour canextend along a majority of at least one surface (e.g., the first majorsurface 603, second major surface 604, or side surface 605) of the body601. In more particular instances, the tortuous contour can define atleast about 60%, such as at least about 70%, at least about 80%, atleast about 90%, or even essentially all of at least one surface of thebody 601.

Moreover, other surfaces not exhibiting a tortuous surface may haveother features, including other features of the embodiments herein(e.g., a fractured surface, an arrowhead shape, etc.) or even asubstantially planar contour. For example, any one of the surfaces ofthe body 601 including but not limited to, the first major surface 603,second major surface 604, and side surface 605, not having a tortuoussurface, may exhibit a substantially planar surface. Still, it will beappreciated that surfaces exhibiting a tortuous surface may haveadditional features, including other features of the embodiments herein,including for example, a fractured surface, an arrowhead shape, and thelike.

In accordance with another aspect, the body 601 can have a first corner631 comprising a first height, measured as the distance between thefirst major surface 603 and the second major surface 604 along the sidesurface 605, and more particularly, the distance between the corner 631and the corner 631 in a direction of the height perpendicular to theline 610. The body 601 can have a second height at the second corner635, measured as the distance between the first major surface 603 andthe second major surface 604 along the side surface 605, and moreparticularly, the distance between the corner 635 and the corner 634 ina direction of the height perpendicular to the line 610. In particular,the first height can be significantly different than the second height.In certain embodiments, the first height can be significantly less thanthe second height.

In accordance with an embodiment, the body 601 of the shaped abrasiveparticle 600 can include a first upper angle 641 between the first majorsurface 603 and the side surface 605 as viewed from the side asillustrated in FIG. 7. The first upper angle 641 can be at least about80 degrees, such as at least about 85 degrees. In other embodiments, thefirst upper angle can be not greater than about 110 degrees. In at leastone embodiment, the side surface 605 can extend at a generallyorthogonal angle relative to at least one of the first major surface 603and the second major surface 604. More particularly, the side surface605 can extend at a generally orthogonal angle relative to the firstmajor surface 603 and the second major surface 604.

The body 601 of the shaped abrasive particle 600 can include a secondlower angle 642 between the second major surface 603 and the sidesurface 605 as viewed from the side as illustrated in FIG. 7. The secondlower angle 642 can be at least about 80 degrees, such as at least about85 degrees. In other embodiments, the second lower angle 642 can be notgreater than about 110 degrees.

The shaped abrasive particles of the embodiments herein can have apercent flashing that may facilitate improved performance. Notably, theflashing can define an area of the particle as viewed along one side,such as illustrated in FIG. 8, wherein the flashing extends from a sidesurface of the body 801 within the boxes 802 and 803. The flashing canrepresent tapered regions proximate to the upper surface and bottomsurface of the body 801. The flashing can be measured as the percentageof area of the body 801 along the side surface contained within a boxextending between an innermost point of the side surface (e.g., 821) andan outermost point (e.g., 822) on the side surface of the body to definethe box 803. The flashing within the box 802 can be measured as thepercentage of area of the body along the side surface contained within abox extending between an innermost point of the side surface 824 and anoutermost point at 823 on the side surface of the body 801. In oneparticular instance, the body 801 can have a particular content offlashing, which can be the percentage of area of the body containedwithin the boxes 802 and 803 compared to the total area of the bodycontained within boxes 802, 803, and 804. According to one embodiment,the percent flashing (f) of the body can be at not greater about 10%. Inanother embodiment, the percent flashing can be less, such as at notgreater than about 9%, not greater than about 8%, not greater than about7%, not greater than about 6%, not greater than about 5%, or even notgreater than about 4%. Still, in one non-limiting embodiment, thepercent flashing can be at least about 0.1%, at least about 0.5%, atleast about 1%, or even at least about 2%. It will be appreciated thatthe percent flashing of the body 801 can be within a range between anyof the above minimum and maximum percentages. Moreover, it will beappreciated that the above flashing percentages can be representative ofan average flashing percentage or a median flashing percentage for abatch of shaped abrasive particles.

The percent flashing can be measured by mounting the shaped abrasiveparticle on its side and viewing the body 801 at the side to generate ablack and white image, such as the orientations illustrate in FIGS. 6and 7. A suitable program for such includes ImageJ software. Thepercentage flashing can be calculated by determining the area of thebody 801 in the boxes 802 and 803 compared to the total area of the bodyas viewed at the side (total shaded area), including the area in thecenter 804 and within the boxes. Such a procedure can be completed for asuitable sampling of particles to generate average, median, and/or andstandard deviation values.

FIG. 9 includes a perspective view illustration of an abrasive particlein accordance with an embodiment. The body 901 includes an upper surface903 a bottom major surface 904 opposite the upper surface 903. The uppersurface 903 and the bottom surface 904 can be separated from each otherby side surfaces 905, 906, and 907. As illustrated, the body 901 of theshaped abrasive particle 900 can have a generally triangular shape asviewed in a plane of the upper surface 903. In particular, the body 901can have a length (Lmiddle), which may be measured at the bottom surface904 of the body 901 and extending from a corner 913 through a midpoint981 of the body 901 to a midpoint at the opposite edge 914 of the body.Alternatively, the body can be defined by a second length or profilelength (Lp), which can be the measure of the dimension of the body froma side view at the upper surface 903 from a first corner 913 to anadjacent corner 912. Notably, the dimension of Lmiddle can be a lengthdefining a distance between a height at a corner (hc) and a height at amidpoint edge (hm) opposite the corner. The dimension Lp can be aprofile length along a side of the particle.

The body 901 can further include a width (w) that is the longestdimension of the body and extending along a side. The shaped abrasiveparticle can further include a height (h), which may be a dimension ofthe shaped abrasive particle extending in a direction perpendicular tothe length and width in a direction defined by a side surface of thebody 901. Notably, body 901 can be defined by various heights dependingupon the location on the body where the height is measured, such as atthe corners versus the interior of the body 901. According to at leastthe embodiment of FIG. 9, the width can be greater than or equal to thelength, the length can be greater than or equal to the height, and thewidth can be greater than or equal to the height.

Moreover, reference herein to any dimensional characteristic (e.g.,height, length, width, etc.) can be reference to a dimension of a singleparticle of a batch, a median value, or an average value derived fromanalysis of a suitable sampling of particles from a batch. Unless statedexplicitly, reference herein to a dimensional characteristic can beconsidered reference to a median value that is a based on astatistically significant value derived from a sample size of suitablenumber of particles of a batch of particles. For certain embodimentsherein, the sample size can include at least 15 randomly selectedparticles from a batch of particles.

In accordance with an embodiment, the body 901 of the shaped abrasiveparticle can have a first corner height (hc) at a first region of thebody defined by a corner 913. Notably, the corner 913 may represent thepoint of greatest height on the body 901. However, the height at thecorner 913 does not necessarily represent the point of greatest heighton the body 901. The corner 913 can be defined as a point or region onthe body 901 defined by the joining of the upper surface 903, and twoside surfaces 905 and 907. The body 901 may further include othercorners, spaced apart from each other, including for example, corner 911and corner 912. As further illustrated, the body 301 can include edges914, 915, and 916 that can separated from each other by the corners 911,912, and 913. The edge 914 can be defined by an intersection of theupper surface 303 with the side surface 906. The edge 915 can be definedby an intersection of the upper surface 903 and side surface 905 betweencorners 911 and 913. The edge 916 can be defined by an intersection ofthe upper surface 903 and side surface 907 between corners 912 and 913.

The shaped abrasive particle can have a body having a particular amountof dishing, wherein the dishing value (d) can be defined as a ratiobetween an average height of the body at the corners (Ahc) as comparedto smallest dimension of height of the body at the interior (hi), whichmay be a position spaced away from the corners 911, 912, and 913 andwithin the interior of the body 901, such as proximate to the midpoint981 within region 919. The average height of the body at the corners(Ahc) can be calculated by measuring the height of the body at allcorners 911, 912, and 913 and averaging the values, and may be distinctfrom a single value of height at one corner (hc). For example, in thecase of a shaped abrasive particle having a triangular shape, threeheight values can be taken at the three corners of the triangular shape.The average height of the body at the corners or at the interior can bemeasured using a STIL (Sciences et Techniques Industrielles de laLumiere—France) Micro Measure 3D Surface Profilometer (white light (LED)chromatic aberration technique). Alternatively, the dishing may be basedupon a median height of the particles at the corner (Mhc) calculatedfrom a suitable sampling of particles from a batch. Likewise, theinterior height (hi) can be a median interior height (Mhi) derived froma suitable sampling of shaped abrasive particles from a batch. Accordingto one embodiment, the dishing value (d) can be not greater than about2, such as not greater than about 1.9, not greater than about 1.8, notgreater than about 1.7, not greater than about 1.6, or even not greaterthan about 1.5, not greater than about 1.3, or even not greater thanabout 1.2. Still, in at least one non-limiting embodiment, the dishingvalue (d) can be at least about 0.9, such as at least about 1.0. It willbe appreciated that the dishing ratio can be within a range between anyof the minimum and maximum values noted above. Moreover, it will beappreciated that the above dishing values can be representative of amedian dishing value (Md) for a batch of shaped abrasive particles.

In another embodiment, the shaped abrasive particle can include a bodycomprising an arrowhead shape. FIG. 10 includes an image of a shapedabrasive particle having an arrowhead shape according to an embodiment.As illustrated, the shaped abrasive particle 1000 can include a body1001 including a first major surface 1003, a second major surfaceopposite the second major surface, and a first side surface 1005, asecond side surface 1006, and a third side surface 1007. The body 1001can have any of the other features of shaped abrasive particlesdescribed herein, and in particular, can utilize one or moresubstantially planar contours and/or tortuous contour surfaces.

In accordance with a particular embodiment, first side surface 1005 canextend into a volume of the body 1001, and the second side surface 1006and the third side surface 1008 can be substantially planar. Inparticular instances, such as illustrated in FIG. 10, at least a portionof the first side surface 1005 can define an arcuate portion, and inparticular may define a substantially concave portion. Accordingly, theangle between the second side surface 1006 and the third side surface1007, as viewed top-down as shown in FIG. 10, can be different than theangle of the corner between the first side surface 1005 and the secondside surface 1006. Additionally, or alternatively, the angle between thesecond side surface 1006 and the third side surface 1007, as viewedtop-down as shown in FIG. 10, can be different than the angle of thecorner between the first side surface 1005 and the third side surface1007. More particularly, the angle between the first side surface 1005and the second side surface 1006 can be less than the angle between thesecond side surface 1006 and the third side surface 1007. Likewise, incertain instances, the angle between the first side surface 1005 and thethird side surface 1007 can be less than the angle between the secondside surface 1006 and the third side surface 1007.

The body 1001 can further include a fractured region 1009 on at least aportion of the first side surface 1005. For example, the body 1001 canhave a fractured region 1009 intersecting at least a portion of an edgedefining the first major surface 1003 or second major surface. Thefractured region 1009 can be characterized by having a surface roughnessgreater than a surface roughness of at least the first major surface1003 or the second major surface of the body 1001. The fractured region1009 can be characterized by irregularly shaped protrusions and groovesextending from the first side surface 1005. In certain instances, thefractured region 1009 can appear as and define a serrated edge. Incertain instances, the fracture region 1009 may be preferentiallylocated at or near the corners of the arms of the body. In still otherinstances, it has been noted that a fractured region 1009 may be formedat a center of the first side surface 1005 defining an arcuate surfacegiving the body 1001 an arrowhead shape. The fractured region 1009 canextend from the second major surface and extend vertically for afraction of the entire height of the first side surface 1005 or even forthe entire height of the first side surface 1005.

It will be appreciated that any of the characteristics of theembodiments herein can be attributed to a batch of shaped abrasiveparticles. A batch of shaped abrasive particles can include, but neednot necessarily include, a group of shaped abrasive particles madethrough the same forming process. In yet another instance, a batch ofshaped abrasive particles can be a group of shaped abrasive particles ofan abrasive article, such as a fixed abrasive article, and moreparticularly, a coated abrasive article, which may be independent of aparticular forming method, but having one or more defining featurespresent in a particular population of the particles. For example, abatch of particles may include an amount of shaped abrasive particlessuitable for forming a commercial grade abrasive product, such as atleast about 20 lbs. of particles.

Moreover, any of the features of the embodiments herein (e.g., aspectratio, planar portions, tortuous contour, arrowhead shape, fracturedregion, two-dimensional shape, etc.) can be a characteristic of a singleparticle, a median value from a sampling of particles of a batch, or anaverage value derived from analysis of a sampling of particles from abatch. Unless stated explicitly, reference herein to the characteristicscan be considered reference to a median value that is a based on astatistically significant value derived from a random sampling ofsuitable number of particles of a batch. Notably, for certainembodiments herein, the sample size can include at least 10, such as atleast about 15, and more typically, at least 40 randomly selectedparticles from a batch of particles.

Any of the features described in the embodiments herein can representfeatures that are present in at least a first portion of a batch ofshaped abrasive particles. Moreover, according to an embodiment, thatcontrol of one or more process parameters can control the prevalence ofone or more features of the shaped abrasive particles of the embodimentsherein. Some exemplary process parameters include, but is not limitedto, the characteristics of the mixture (e.g., viscosity, storagemodulus, coil value), the rate of translation, the rate of extrusion,the batch efficiency, the batch productivity, the composition of theejection material, the predetermined force, the ejection materialopening width relative to the shaping assembly opening width, the gapdistance, and a combination thereof.

The first portion may be a minority portion (e.g., less than 50% and anywhole number integer between 1% and 49%) of the total number ofparticles in a batch, a majority portion (e.g., 50% or greater and anywhole number integer between 50% and 99%) of the total number ofparticles of the batch, or even essentially all of the particles of abatch (e.g., between 99% and 100%). The provision of one or morefeatures of any shaped abrasive particle of a batch may facilitatealternative or improved deployment of the particles in an abrasivearticle and may further facilitate improved performance or use of theabrasive article.

A batch of particulate material can include a first portion including afirst type of shaped abrasive particle and a second portion including asecond type of shaped abrasive particle. The content of the firstportion and second portion within the batch may be controlled at leastin part based upon certain processing parameters. Provision of a batchhaving a first portion and a second portion may facilitate alternativeor improved deployment of the particles in an abrasive article and mayfurther facilitate improved performance or use of the abrasive article.

The first portion may include a plurality of shaped abrasive particles,wherein each of the particles of the first portion can havesubstantially the same features, including for example, but not limitedto, the same two-dimensional shape of a major surface. Other featuresinclude any of the features of the embodiments herein. The batch mayinclude various contents of the first portion. For example, the firstportion may be present in a minority amount or majority amount. Inparticular instances, the first portion may be present in an amount ofat least about 1%, such as at least about 5%, at least about 10%, atleast about 20%, at least about 30%, at least about 40%, at least about50%, at least about 60%, or even at least about 70% for the totalcontent of portions within the batch. Still, in another embodiment, thebatch may include not greater than about 99%, such as not greater thanabout 90%, not greater than about 80%, not greater than about 70%, notgreater than about 60%, not greater than about 50%, not greater thanabout 40%, not greater than about 30%, not greater than about 20%, notgreater than about 10%, not greater than about 8%, not greater thanabout 6%, or even not greater than about 4% of the total portions withinthe batch. The batch can include a content of the first portion within arange between any of the minimum and maximum percentages noted above.

The second portion of the batch can include a plurality of shapedabrasive particles, wherein each of the shaped abrasive particles of thesecond portion can have substantially the same feature, including forexample, but not limited to, the same two-dimensional shape of a majorsurface. The second portion can have one or more features of theembodiments herein, which can be distinct compared to the plurality ofshaped abrasive particles of the first portion. In certain instances,the batch may include a lesser content of the second portion relative tothe first portion, and more particularly, may include a minority contentof the second portion relative to the total content of particles in thebatch. For example, the batch may contain a particular content of thesecond portion, including for example, not greater than about 40%, suchas not greater than about 30%, not greater than about 20%, not greaterthan about 10%, not greater than about 8%, not greater than about 6%, oreven not greater than about 4%. Still, in at least on non-limitingembodiment, the batch may contain at least about 0.5%, such as at leastabout 1%, at least about 2%, at least about 3%, at least about 4%, atleast about 10%, at least about 15%, or even at least about 20% of thesecond portion for the total content of portions within the batch. Itwill be appreciated that the batch can contain a content of the secondportion within a range between any of the minimum and maximumpercentages noted above.

Still, in an alternative embodiment, the batch may include a greatercontent of the second portion relative to the first portion, and moreparticularly, can include a majority content of the second portion forthe total content of particles in the batch. For example, in at leastone embodiment, the batch may contain at least about 55%, such as atleast about 60% of the second portion for the total portions of thebatch.

It will be appreciated that the batch can include additional portions,including for example a third portion, comprising a plurality of shapedabrasive particles having a third feature that can be distinct from thefeatures of the particles of the first and second portions. The batchmay include various contents of the third portion relative to the secondportion and first portion. The third portion may be present in aminority amount or majority amount. In particular instances, the thirdportion may be present in an amount of not greater than about 40%, suchas not greater than about 30%, not greater than about 20%, not greaterthan about 10%, not greater than about 8%, not greater than about 6%, oreven not greater than about 4% of the total portions within the batch.Still, in other embodiments the batch may include a minimum content ofthe third portion, such as at least about 1%, such as at least about 5%,at least about 10%, at least about 20%, at least about 30%, at leastabout 40%, or even at least about 50%. The batch can include a contentof the third portion within a range between any of the minimum andmaximum percentages noted above. Moreover, the batch may include acontent of diluent, randomly shaped abrasive particles, which may bepresent in an amount the same as any of the portions of the embodimentsherein.

For example, in accordance with one particular aspect, a batch of shapedabrasive particles can include a first portion, which can include ashaped abrasive particle having a tortuous contour. The first portioncan include any one or combination of features described in accordancewith shaped abrasive particles having a tortuous contour. The firstportion can be a majority of a total number of shaped abrasive particlesof the batch. Alternatively, the first portion can be a minority of atotal number of shaped abrasive particles of the batch. In yet oneparticular aspect, as noted herein, the first portion can be at least 1%of a total number of shaped abrasive particles of the batch. In yetanother particular embodiment, as noted herein, the first portion can benot greater than about 99% of a total number of shaped abrasiveparticles of the batch.

Furthermore, in one particular aspect, the batch can also include asecond portion of shaped abrasive particles, wherein the second portionof shaped abrasive particles have a discrete shape feature differentthan the tortuous contour of the shaped abrasive particles of the firstportion. More particularly, exemplary discrete shape features caninclude, but are not limited to, dish-shaped particles, substantiallyplanar particles, concavo-convex particles, shaped abrasive shards,molded shaped abrasive particles, screen-printed shaped abrasiveparticles, cast-and-cut shaped abrasive particles, multilayered abrasiveparticles, arrowhead-shaped particles, shaped abrasive particles havinga complex shape, diluent abrasive particles, and a combination thereof.

It will be appreciated that the batch of shaped abrasive particles arepart of a fixed abrasive article, which can include, but is not limitedto, bonded abrasive articles (see, for example, FIG. 5), coated abrasivearticles (see, for example FIG. 4), and a combination thereof. In oneparticular embodiment, the fixed abrasive article can include a coatedabrasive article, wherein the first portion of the batch includes aplurality of shaped abrasive particles, and each of the shaped abrasiveparticles of the plurality of shaped abrasive particles are arranged ina controlled orientation relative to a backing. Some exemplary types ofcontrolled orientation can include at least one of a predeterminedrotational orientation, a predetermined lateral orientation, and apredetermined longitudinal orientation. In such instances, the shapedabrasive particles may be oriented with respect to each other or withrespect to a particular predetermined abrasive direction (i.e.,direction for conducting material removal relative to a workpiece).Moreover, in certain instances, the shaped abrasive particle can becoupled to the backing in a side orientation relative to the backing,such that a side surface is closest to the surface of the backing. In analternative embodiment, at least a significant portion of the shapedabrasive particles of the first portion can be coupled to the backing ina flat orientation relative to the backing, such that a major surface ofthe body is closest to the surface of the backing.

According to another aspect, the first portion of the batch can have apredetermined classification characteristic selected from the groupconsisting of average particle shape, average particle size, particlecolor, hardness, friability, toughness, density, specific surface area,and a combination thereof. Likewise, any of the other portions of thebatch may be classified according to the above noted classificationcharacteristics.

Example 1

A mixture in the form of a gel is obtained having approximately 52 wt %solids loading of boehmite commercially available as Catapal B fromSasol Corp. combined with 48 wt % water containing a minority content ofnitric acid and organic additives. The gel has a viscosity ofapproximately 70,000 Pa·s and a storage modulus of approximately 450,000Pa, and a coil value of approximately 3000 N.

The gel is extruded from a die using a pressure of approximately 90 psi(552 kPa) into a screen comprising a metal material and having openingsare in the shape of an equilateral triangle, and wherein the sides ofthe triangle have a length of approximately 3.4 mm and the openings havea depth of approximately 0.6 mm. During extrusion in the applicationzone, the screen is abutting a backing plate.

The gel is extruded into the openings and the screen with the gel in theopenings is translated to an ejection zone at a rate of 1 m/min. Priorto entering the ejection zone, the gel passes through a heating zoneincluding infrared lamps and having an average temperature of betweenapproximately 50-90° C. The gel and the shaping assembly pass throughthe heating zone in approximately 30 seconds and essentially novolatiles are removed from the gel. Note that the heating zone isoptional and may not be utilized in all instances.

The ejection zone includes an air knife, operated at a pressure of 90psi and exerting approximately 20 N of force and a resulting pressure ofapproximately 0.3 N/mm² on the gel in the mold. The ejection material isair. The air knife has an ejection material opening that isapproximately 2% of the shaping assembly opening width. As the gelcontained within the openings of the screen passes the air knife, thegel is ejected and precursor shaped abrasive particles are formed.

The precursor shaped abrasive particles are then dried for approximately20 hours in air at approximately 95° C. under standard atmosphericconditions of pressure and composition. The precursor shaped abrasiveparticles were calcined in a box furnace at approximately 600° C. for an1 hour, and thereafter, the precursors shaped abrasive particles weresintered in a tube furnace up to 1320° C. for 3 to 20 minutes.

FIG. 11A includes images (inverted color) of 15 particles, each viewedfrom the side. The images were taken with a light microscope. The 15particles were taken from a sample of the batch made according toExample 1. As illustrated, at least a portion of the batch of shapedabrasive particle, and more particularly, 8 discrete shaped abrasiveparticles 1101, 1102, 1103, 1104, 1105, 1106, 1107, and 1108 of the 15sampled particles, demonstrated a tortuous contour of at least onesurface (e.g., the first major surface or second major surface).

FIG. 11B includes a top view image of a sample of grains from the batchof Example 1. Notably, a portion of the shaped abrasive particles of thebatch have an arrowhead shape, including for example, the shapedabrasive particles 1121, 1122, 1123, and 1124.

The batch of shaped abrasive particles were then incorporated into acoated abrasive article as Sample 1 and tested according to theconditions provided below in Table 1. Notably, 2 sample coated abrasiveswere tested in each case to derive the results. Sample 1 represents acoated abrasive including the shaped abrasive particles of Example 1,and having a median width of approximately 1.5 mm, a median height ofapproximately 300 microns, a median flashing percentage of less than10%, a dishing value of approximately 1.2, wherein approximately 80% ofthe abrasive particles were positioned in a predetermined, sideorientation on the backing such that the side surface was in contactwith the backing. Sample 1 had a normalized weight of shaped abrasiveparticles of 40 lbs/ream.

A second sample, (CS1) is a Cubitron II belt commercially available from3M as 3M984F. Approximately 70% of the shaped abrasive particles, whichhave a generally planar shape, were positioned in a predetermined sideorientation on the backing. The shaped abrasive particles appear to bemolded particles, such as those disclosed in U.S. Pat. No. 5,366,523 toRowenhorst.

TABLE 1 Test platform: Okuma Screening Test Test conditions: Dry, Riseand Fall Constant MRR′ = 4 inch3/min inch Belt speed = Vs = 7500 sfpm(38 m/s) Work material: 304 ss, Hardness: 104 HRB Size: 0.5″ × 0.5″ × 6inches Contact width = 0.5″ inch Measurements: Power, Grinding Forces,MRR′ and SGE

FIG. 12 includes a plot of specific grinding energy versus cumulativematerial removed (at a material removal rate of 4.0 inch3/min/inch) forSample 1 and Sample CS1. As shown, while Sample 1 had a slightly higherspecific grinding energy relative to Sample CS1, the specific grindingenergy was relatively steady through 75% of the life of the belt. Bycontrast, Sample CS1 demonstrates a steadily rising specific grindingenergy throughout the majority of the life the abrasive article.Moreover, and also remarkable, Sample 1 has essentially the same life(i.e., Cum MR) as compared to Sample CS1.

FIG. 13 includes an image of a sample of shaped abrasive particlesformed according to Example 1. Notably, at least a portion of the shapedabrasive particles of Sample 1 demonstrate a tortuous contour, includingfor example, shaped abrasive particles 1301, 1302, and 1303.

Moreover, as further illustrated in FIG. 13, a portion of the shapedabrasive particles of Sample 2 have an arrowhead shape, including forexample, the shaped abrasive particles 1311, 1312, 1313, 1314, 1315, and1316. Additionally, as illustrated in FIG. 13, a portion of the shapedabrasive particles of Sample 2 have side surfaces having a fracturedregion, including for example, the shaped abrasive particles 1303, 1314,1316, 1321, 1322, 1323, and 1324.

The present application represents a departure from the state of theart. While the industry has recognized that shaped abrasive particlesmay be formed through processes such as molding and screen printing, theprocesses of the embodiments herein are distinct from such processes.Notably, the embodiments herein utilize particular systems and methods,having a combination of features, including but not limited to the typeand rheological characteristics of the mixture, aspects of theapplication zone, length of the belt, relative size of openings in theejection assembly and the openings in the first portion of the shapingassembly, predetermined force of ejection material, batch efficiency,batch productivity, and the like. Moreover, the resulting precursorshaped abrasive particles and sintered shaped abrasive particles havefeatures unique to the forming process, including for example, tortuouscontours, fractured regions, arrowhead shapes, dishing, flashingpercentage, and others described herein. Notably, it is remarkable andunexpected that shaped abrasive particles can be formed with suchprecision and speed, which results in little to no change in the qualityof an abrasive product incorporating the mass-produced particles ascompared to other conventional abrasive products incorporating moldedshaped abrasive particles. Furthermore, it has been discovered that inaddition to the production capabilities of the new process, the systemand process may be controlled in a manner to allow for control ofcertain features of shaped abrasive particles and formation of batchesof shaped abrasive particles having certain features or combinations offeatures.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true scope of the present invention. Thus, to the maximum extentallowed by law, the scope of the present invention is to be determinedby the broadest permissible interpretation of the following claims andtheir equivalents, and shall not be restricted or limited by theforegoing detailed description.

The Abstract of the Disclosure is provided to comply with Patent Law andis submitted with the understanding that it will not be used tointerpret or limit the scope or meaning of the claims. In addition, inthe foregoing Detailed Description of the Drawings, various features maybe grouped together or described in a single embodiment for the purposeof streamlining the disclosure. This disclosure is not to be interpretedas reflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may be directed toless than all features of any of the disclosed embodiments. Thus, thefollowing claims are incorporated into the Detailed Description of theDrawings, with each claim standing on its own as defining separatelyclaimed subject matter.

What is claimed is:
 1. A method comprising: extruding a mixture having aviscosity of at least about 4×10³ Pa s into an opening in a shapingassembly within an application zone; and removing the mixture from theopening by applying an external force to the mixture to form a precursorshaped abrasive particle.
 2. The method of claim 1, wherein the mixturecomprises a gel comprising a ceramic material and a liquid.
 3. Themethod of claim 2, wherein the gel is a shape-stable material.
 4. Themethod of claim 2, wherein the gel comprises a ceramic powder materialas an integrated network of discrete particles.
 5. The method of claim1, wherein the mixture comprises an amount of a ceramic material of atleast about 25 wt % for the total weight of the mixture and not greaterthan about 80 wt % for the total weight of the mixture.
 6. The method ofclaim 1, wherein the mixture comprises not greater than about 30 wt %organic materials for the total weight of the mixture.
 7. The method ofclaim 1, wherein the mixture comprises a storage modulus of at leastabout 1×10⁴ Pa.
 8. The method of claim 1, wherein the mixture comprisesa change in weight of less than about 5% for a total weight of themixture for a duration that the mixture is in the opening of the shapingassembly.
 9. The method of claim 1, wherein the mixture comprises achange in volume of less than about 5% for a total volume of the mixturefor a duration that the mixture is in the opening of the shapingassembly.
 10. The method of claim 1, wherein an average residence timeof the mixture in the opening of the shaping assembly is less than about18 minutes.
 11. The method of claim 2, wherein the ceramic materialcomprises an oxide, a nitride, a carbide, a boride, an oxycarbide, anoxynitride, or a combination thereof.
 12. The method of claim 2, whereinthe ceramic material comprises alumina.
 13. The method of claim 1,wherein the mixture comprises a yield stress of at least about 1.5×10³Pa and not greater than about 50×10³ Pa.
 14. The method of claim 1,wherein the external force comprises a pressure of at least about 10 kPaand not greater than 10,000 kPa.
 15. The method of claim 1, wherein themixture comprises a coil value of at least about 1800 N.